JP2006313877A - Antistatic parts - Google Patents

Abstract

An object of the present invention is to provide an anti-static component that is thin, has high mechanical strength, and has excellent electrical characteristics and quality.
A varistor section comprising a ceramic insulating substrate, a varistor layer provided on the ceramic insulating substrate by sintering and integration, internal electrodes 11a and 11b, and via conductors 13a and 13b, and the varistor section 10. At least a pair of external electrodes 12a and 12b provided on the outer surface of the electrode, and the internal electrodes 11a and 11b have at least a pair provided so as to face each other with the varistor layer 14 interposed therebetween. 12a and 12b and the internal electrodes 11a and 11b are electrically connected to each other, and the varistor part has a thickness of 100 microns or less. It is an anti-static component with excellent mechanical characteristics and quality.
[Selection] Figure 1

Description

  The present invention relates to a static electricity countermeasure component for protecting an electronic device from static electricity.

  In recent years, electronic devices such as mobile phones have been rapidly reduced in size and performance, and accordingly, the electronic device circuits have become denser and the withstand voltage of the electronic devices has decreased. Therefore, the destruction of the electric circuit inside the device due to the electrostatic pulse generated when the human body and the terminal of the electronic device contact each other is increasing.

  Conventionally, as countermeasures against such electrostatic pulses, a method of providing a multilayer chip varistor or the like between a line where static electricity enters and the ground, bypassing the static electricity, and suppressing the voltage applied to the electrical circuit of the device has been performed. Yes.

For example, Patent Document 1 is known as prior art document information related to a conventional multilayer chip varistor used for countermeasures against electrostatic pulses.
JP-A-8-31616

  Recently, with the miniaturization and high performance of electronic devices, the number of countermeasures against electrostatic pulses has increased, and there is a demand for not only a single component but also an array component that incorporates multiple components. In particular, it is increasing. Furthermore, there is an increasing demand for small and thin electronic devices, and there is also an increasing demand for thin anti-static components.

  However, in the conventional multilayer chip varistor, the bending strength of the zinc oxide-based material constituting the conventional multilayer chip varistor is small, and a certain amount of thickness is necessary from the viewpoint of the physical strength of the component, and it is difficult to reduce the thickness. It was. For example, in the case of a commercially available multilayer chip varistor having a length of 1.6 mm and a width of about 0.8 mm, a thickness of about 0.8 mm or more is required. When attempting to make it thinner than this, it is necessary to further reduce the size, and it is difficult to form a thin and large component. For this reason, there has been a problem that it is difficult to obtain an array product incorporating a large number of elements.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide an anti-static component that is thin, has high mechanical strength, and has excellent electrical characteristics and quality.

  In order to achieve the above object, the present invention has the following configuration.

  The antistatic component of the present invention is provided on a ceramic insulating substrate, a varistor layer formed by sintering and integrating on the ceramic insulating substrate, an internal electrode and a via conductor, and an outer surface of the varistor portion. At least a pair of external electrodes, and the internal electrodes have at least a pair of internal electrodes provided to face each other with the varistor layer interposed therebetween, and the external electrodes and the internal electrodes are electrically connected to each other by the via conductors. In addition, the varistor part has a thickness of 100 microns or less, and the varistor part is sintered and integrated on a ceramic insulating substrate having a high mechanical strength. Therefore, it is a thin, thin, high mechanical strength and practically excellent anti-static component. Since the varistor is formed by sandwiching the varistor layer between a pair of opposed internal electrodes, the varistor is an anti-static component with excellent electrical characteristics and quality.

  In the above configuration, it is desirable that the protrusion of the connecting portion between the via conductor and the external electrode on the outer surface of the varistor portion is 3 microns or less. As a result, the number of defects during mounting is reduced, and an anti-static component with superior quality is obtained.

  In the above configuration, it is desirable that the protrusion of the connection portion between the via conductor and the internal electrode at the varistor layer is 10 microns or less. As a result, structural defects such as cracks in the varistor layer are reduced, there are few defects such as deterioration of life characteristics, and an antistatic component with excellent characteristics and quality is obtained.

  In the above configuration, the diameter of the via conductor is desirably 120 microns or less. As a result, protrusion of the via conductor to the inside and the outside is reduced, structural defects such as defects during mounting and internal cracks are reduced, and an anti-static component with excellent characteristics and quality is obtained.

  Further, in the manufacture of the above-described antistatic component, the via conductor is preferably formed using a silver paste having a silver content of 85% or less. As a result, even if the varistor part shrinks greatly in the thickness direction during integral sintering, the silver content of the via conductor part is small, so the protrusion of the via conductor to the inside and the outside can be suppressed, and during mounting There are fewer structural defects such as defects and internal cracks, and it is possible to manufacture anti-static parts with superior characteristics and quality.

  In the above configuration, it is desirable to further provide a protective layer on the outer surface of the varistor part. Thereby, the influence of dissolution by the plating solution of the varistor part in the subsequent plating process can be suppressed, it can be produced with high yield without causing problems such as plating flow, and the environmental resistance characteristics as a product can be enhanced, Furthermore, it is an anti-static component with excellent characteristics and quality.

  As described above, the present invention is provided on the ceramic insulating substrate, the varistor layer formed by integrating the sintered body on the ceramic insulating substrate, the internal electrode and the via conductor, and the outer surface of the varistor portion. At least a pair of external electrodes, and the internal electrodes have at least a pair of internal electrodes provided to face each other with the varistor layer interposed therebetween, and the external electrodes and the internal electrodes are electrically connected to each other by the via conductors. The anti-static component with a thickness of the varistor portion of 100 microns or less, a thin, high mechanical strength and practically excellent anti-static component, and the variation in the electrical characteristics of the varistor is small, It has the effect of becoming an anti-static component with excellent characteristics and quality.

  Hereinafter, the anti-static component in the embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1 is a cross-sectional view of a static electricity countermeasure component according to Embodiment 1 of the present invention, FIG. 2 is an external perspective view of the static electricity countermeasure component according to Embodiment 1 of the present invention, and FIG. 3 is a static electricity countermeasure according to Embodiment 1 of the present invention. FIG. 4 is a schematic exploded perspective view of the static electricity countermeasure component according to Embodiment 1 of the present invention.

  1, 2, and 4, 10 is a varistor portion, 11 a and 11 b are internal electrodes, 12 a and 12 b are external electrodes, 13 a and 13 b are via conductors, 14 is a varistor layer, 15 is a ceramic insulating substrate, and 16 is protective Is a layer.

  As shown in FIG. 1, FIG. 2 and FIG. 4, the antistatic component in the first embodiment is formed by laminating a ceramic insulating substrate 15, a varistor layer 14, internal electrodes 11a and 11b, and a protective layer 16, and via conductors. The varistor part 10 in which 13a and 13b are formed is integrated as a ceramic sintered body, and a pair of external electrodes 12a and 12b are provided on the outer surface of the varistor part 10, and a pair of opposed internal electrodes 11a And 11b with a varistor layer 14 interposed therebetween, and the internal electrodes 11a and 11b are electrically connected to the external electrodes 12a and 12b by via conductors 13a and 13b, respectively, to have a varistor. Yes.

  And the antistatic component in this Embodiment 1 is set as the structure which does not arrange | position the internal electrode 11b which opposes in the site | part just under the connection part of the internal electrode 11a and the via conductor 13a.

  As described above, the antistatic component in the first embodiment is a ceramic sintered body in which the varistor portion 10 is sintered and integrated on the ceramic insulating substrate 15 having a high mechanical strength. It has a high mechanical strength and is an excellent anti-static component for practical use. Since the varistor is formed with the varistor layer 14 sandwiched between the pair of internal electrodes 11a and 11b facing each other, the variation in the electrical characteristics of the varistor is small, and the anti-static component having excellent characteristics and quality.

  Moreover, even if the via conductor protrudes to the opposing internal electrode side, the opposing internal electrode 11b is not disposed in the portion immediately below the connection portion between the internal electrode 11a and the via conductor 13a. Therefore, it is possible to prevent the proximity between the internal electrodes, and there are few defects such as a short circuit, and the electrostatic countermeasure component has excellent characteristics and quality.

  And the circuit of the antistatic component in this Embodiment 1 becomes an equivalent circuit shown in FIG. In FIG. 3, 201 is a varistor, 202 is an input / output external electrode, and 203 is a ground external electrode. As described above, the external electrodes 12a and 12b have the same configuration in terms of equivalent circuits. Therefore, when actually connected to a circuit, one of them is the input / output external electrode 202, and the other is It becomes the ground external electrode 203.

  Next, a method for manufacturing an antistatic component in Embodiment 1 of the present invention will be described with reference to FIG.

  First, a zinc oxide raw sheet made of a ceramic powder mainly composed of zinc oxide and an organic binder was prepared and prepared. Moreover, the glass-ceramic raw sheet which consists of a glass-ceramic powder which has an alumina and a borosilicate glass as a main component, and an organic binder was produced and prepared. At this time, the thickness of each raw sheet was about 30 μm. Each of these green sheets is fired, the zinc oxide green sheet becomes the varistor layer 14, and the glass-ceramic green sheet becomes the protective layer 16.

  As shown in FIG. 4, on the zinc oxide raw sheet used as the varistor layer 14a, the conductor layer used as the internal electrode 11b was formed by the screen printing method using the silver paste. A varistor layer in which a silver paste to be a via conductor 13b is filled in a position electrically connected to the internal electrode 11b and the external electrode 12b, and a conductor layer to be the internal electrode 11a is formed by screen printing using the silver paste. A raw zinc oxide sheet to be 14b was laminated. Further, a silver paste serving as a via conductor 13a is filled in a position electrically connected to the internal electrode 11a and the external electrode 12a, and a via conductor 13b is electrically connected to the internal electrode 11b and the external electrode 12b. A raw zinc oxide sheet to be a varistor layer 14c filled with a silver paste was stacked. Further, a glass-ceramic raw sheet serving as a protective layer 16 is formed by filling a silver paste serving as the via conductors 13a and 13b thereon and forming a conductor layer serving as the external electrodes 12a and 12b by screen printing using the silver paste. The laminated body which becomes a varistor part 10 by laminating was produced.

  Next, an alumina substrate was used as the ceramic insulating substrate 15, and the laminate was bonded onto the alumina substrate to obtain a laminate block. The thickness of the alumina substrate was about 180 μm, the thickness of the conductor layer was about 2.5 μm, the silver content of the silver paste used for the via conductor was 85 wt%, and the via diameter was 120 microns. Further, the printed pattern of the conductor layer was a pattern shape in which a large number of shapes illustrated in FIG. 4 were arranged vertically and horizontally so as to have the shape shown in FIG.

  Next, the laminate block was heated in the atmosphere to remove the binder, and then heated to 930 ° C. in the atmosphere and baked to obtain an integrated sintered body. Subsequently, after nickel and tin are plated on the external electrode portion of the formed sintered body, it is cut and separated to a desired size, and the antistatic component in the first embodiment shown in FIGS. 1 and 2 is produced. (Example 1).

  The produced antistatic component (Example 1) in the first embodiment had a longitudinal dimension of about 1.6 mm, a widthwise dimension of about 0.8 mm, and a thicknesswise dimension of about 0.25 mm. And the thickness of the varistor part was about 70 microns. Further, when the protrusion on the outer surface of the varistor portion of the connection portion between the via conductor and the external electrode of this antistatic component was measured, it was within 3 microns. When these were mounted on a resin-based printed wiring board, mounting was possible without any problems.

  Also, this antistatic component was polished from the end face, its cross section was observed, and the protrusion at the varistor layer at the connection portion between the via conductor and the internal electrode was measured. Did not exist.

And when 300 static electricity countermeasure components (Example 1) in this Embodiment 1 were produced, there was no short circuit defect. The voltage when the varistor voltage V _{1 mA} between the external electrodes 12a and 12b, that is, the current of ₁ mA flows, was between about 22V and about 30V. Further, 20 samples were randomly taken out and subjected to a high-temperature and high-humidity test in which a temperature of 60 ° C., a humidity of 90% and a DC of 10 V was loaded. As a result, no varistor voltage V _1mA changed by 20% or more after 500 hours had elapsed.

  Further, when the production conditions are changed variously to change the thickness of the raw zinc oxide sheet to about 100 microns (Example 2) and about 50 microns (Example 3), the diameter of the via conductor is 100. In the case of micron (Example 4) and 80 micron (Example 5), the silver content of the silver paste used for forming the via conductor was further set to 80% (Example 6) and 75% (Example 7). In this case, the antistatic component in the first embodiment was produced.

  In addition, for comparison, samples of 10 types of comparative examples are manufactured for cases where the varistor portion is thickened, the diameter of the via conductor is increased, and the silver content of the silver paste used for forming the via conductor is increased. did. The production conditions of these comparative examples are as follows: the thickness of the zinc oxide raw sheet is increased while the thickness of the alumina is left unchanged, and the thickness of the varistor part is about 110 microns (Comparative Example 1), about 150 microns (Comparative Example 2). When the diameter of the via conductor is 200 microns (Comparative Example 4) and 300 microns (Comparative Example 5), the silver content of the silver paste used for forming the via conductor is about 200 microns (Comparative Example 3). There are 10 types of cases of 90% (Comparative Example 6) and 92.5% (Comparative Example 7), and a combination thereof (Comparative Example 8, Comparative Example 9 and Comparative Example 10).

  And it evaluated about the static electricity countermeasure components (Example 1- Example 7) in this Embodiment 1, and 10 types of comparative examples (Comparative example 1- Comparative example 10). The evaluation was performed by measuring 20 samples each, the size of the warp, the presence or absence of cutting failure, the average value of the outward protrusion on the outer surface of the via conductor part, the inward protrusion of the via conductor part on the varistor layer. The average value, mounting defect rate, and crack occurrence rate were examined. The evaluation results of the static electricity countermeasure components and the comparative example in the first embodiment are shown in (Table 1) together with the manufacturing conditions.

  As shown in (Table 1), all of the anti-static parts in the first embodiment have small warpage, and there are no cutting defects, internal cracks, and mounting defects when mounted on the board.

  On the other hand, in the comparative example, when the thickness of the varistor part was 110 to 200 microns (Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 8 and Comparative Example 9), the warpage was large. For this reason, when cutting into individual pieces, cracks or cracks occurred, resulting in poor cutting. Even those that could be cut had large warping as individual pieces and had a mounting failure rate of 5 to 25%.

  Further, when the diameter of the via conductor is 200 microns and 300 microns (Comparative Example 4, Comparative Example 5, Comparative Example 8, Comparative Example 9 and Comparative Example 10), Comparative Example 8 in which the thickness of the varistor part is 150 microns. In other words, the protrusion to the inside of the via conductor portion was as large as 11 to 20 microns, and the crack generation rate inside the element was 5 to 20%. In addition, the protrusion of the via conductor portion to the outside is increased, which may cause mounting defects.

  Further, when the silver content of the silver paste used for forming the via conductor is 90% and 92.5% (Comparative Example 6, Comparative Example 7, Comparative Example 8, Comparative Example 9 and Comparative Example 10), the varistor is also used. Except for Comparative Example 8 where the thickness of the portion was 150 microns, the protrusion to the inside of the via conductor portion was as large as 12 to 20 microns, and the crack occurrence rate inside the element was 5 to 30%. Except for Comparative Example 8 where the thickness of the varistor portion is 150 microns and Comparative Example 9 where the thickness is 110 microns, the via conductors protrude to the outside as large as 6-9 microns, and the mounting defect rate is reduced to 5-20%. became.

  In addition, as for the anti-static component (Examples 2 to 7) and the 10 types of comparative examples (Comparative Examples 1 to 10) in the first embodiment, 20 pieces are randomly taken out and the temperature is A high-temperature and high-humidity test with 60 ° C., 90% humidity and 10 V DC was performed.

As a result, for the antistatic component (Examples 2 to 7), Comparative Example 1, Comparative Example 2 and Comparative Example 8 in the first embodiment, in which no crack is generated, the varistor voltage V _{1 mA} is None changed by more than 20%. However, for Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, Comparative Example 6, Comparative Example 7, Comparative Example 9 and Comparative Example 10 having a high crack occurrence rate, the initial value of the varistor voltage V _{1 mA} after 500 hours has elapsed. The rate of change with respect to the temperature was 20% or more, and the presence of cracks adversely affected the results of the high-temperature and high-humidity test.

  As described above, it is preferable that the varistor portion has a thickness of 100 microns or less, whereby it is possible to prevent the product from warping and to be an excellent anti-static component with no chipping or cracking.

  In addition, it is desirable that the protruding portion of the connection portion between the via conductor and the external electrode on the outer surface of the varistor portion is 3 microns or less, thereby providing an anti-static component with excellent mountability.

  Further, the protrusion of the connection portion between the via conductor and the internal electrode in the varistor layer is desirably 10 microns or less, and the diameter of the via conductor is desirably 120 microns or less. As a result, structural defects such as cracks in the varistor layer are reduced, there are few defects such as deterioration of life characteristics, and an antistatic component with excellent characteristics and quality is obtained.

  Further, the via conductor is desirably formed using a silver paste having a silver content of 85% or less, so that even if the varistor portion is greatly shrunk in the thickness direction during the integral sintering, the via conductor portion Produces anti-static parts with excellent characteristics and quality due to the low silver content, which prevents the via conductor from protruding into and out of the via conductor, reduces mounting defects and internal defects such as internal cracks, etc. be able to.

  Next, an electrostatic test was conducted and evaluated for Example 1 of the antistatic component of the first embodiment produced above.

  The static electricity test was performed using the circuit shown in FIG. After connecting the switch 103 and applying a predetermined voltage from the DC power source 101 via the resistor 102 to charge the capacitance box 104 having a capacitance of 150 pF, the switch is switched to open the switch 103 and connect the switch 105. Then, the charge charged in the capacitor box 104 is applied as an electrostatic pulse to the protected device 110 through the signal line 108 via the resistor 106.

  As shown in FIG. 5, the antistatic component of the first embodiment has the input / output external electrode 202 connected to the signal line 108 side and the ground external electrode 203 connected to the ground line 107 as the evaluation sample 109. Connected.

By measuring the voltage waveform between the signal line 108 immediately before the protected device 110 and the ground line 107 when the electrostatic pulse is applied, the electrostatic pulse is bypassed and the voltage applied to the protected device 110 is suppressed. That is, the effect of suppressing the absorption of the antistatic component, which is the evaluation sample 109, against electrostatic pulses was evaluated. For comparison, the effect of suppressing the absorption of electrostatic pulses when a laminated varistor of a comparative example having a varistor voltage V _{1 mA} of 27 V was connected between the signal line 108 and the ground line 107 was also evaluated. The absorption suppression effect was confirmed by comparing the peak voltage values of electrostatic pulses to which 8 kV was applied by the electrostatic test circuit shown in FIG.

  As a comparison, when the laminated varistor is connected between the signal line 108 and the ground line 107, the peak voltage value applied to the protected device 110 is about 220V, whereas the countermeasure against static electricity in the first embodiment is applied. The peak voltage value applied to the protected device 110 when the components were provided was about 230V. In other words, it was confirmed that although it has a completely different configuration, it has the effect of suppressing the absorption of electrostatic pulses that is almost the same as that of a conventional multilayer varistor.

  As described above, the anti-static component in the first embodiment can be made extremely thin, has a sufficient function as an anti-static component, has no cracks, and is easy to mount and has a high temperature and high humidity load. It was able to be an anti-static part with excellent quality such as testing.

  In addition, although the anti-static component in the said Embodiment 1 was the structure which formed one element in one component, in the range of a desired dimension and performance as needed, a plurality of arrays, such as a 2 or 4 array It can also be configured as an array product incorporating elements.

  In addition, although the number of varistor layers having a varistor function sandwiched between the internal electrodes of the varistor portion is one, there may be two or more effective varistor layers. Further, although an alumina substrate is used as the ceramic insulating substrate, ferrite or a high dielectric constant dielectric material may be used as long as sufficient bending strength is obtained. Moreover, although the silver paste was used for the electrode paste, other metal pastes such as a silver-palladium paste and a platinum paste may be used. The lowermost internal electrode may be formed at the interface between the varistor portion and the ceramic insulating substrate.

  In the first embodiment, the manufacturing method in which the external electrode is simultaneously formed as a ceramic sintered body together with the varistor layer, the internal electrode, and the via conductor has been shown. However, from the varistor layer, the internal electrode, and the via conductor, After forming the varistor portion as a ceramic sintered body, the external electrode may be formed.

  In addition, the protective layer is formed to protect the varistor portion from the plating solution in the subsequent plating step and to improve the environmental resistance characteristics of the product. And in the said Embodiment 1, although the varistor layer, an internal electrode, a via conductor, and the manufacturing method which fired simultaneously with the external electrode and formed the protective layer are shown, a varistor layer, an internal electrode, a via conductor, and an external electrode It is good also as a manufacturing method which obtained by baking and obtained a sintered compact, printed glass paste after that, and baked at desired temperature, and formed the protective layer.

  Moreover, although the process of performing the plating is performed before the element is separated and cut into a desired size, it may be performed after the separation and cutting.

  The anti-static component according to the present invention is a thin anti-static component with high mechanical strength and excellent electrical characteristics. Therefore, small and thin electronic devices such as mobile phones can be destroyed from malfunction or malfunction due to electrostatic pulses. It is particularly useful as a protective part.

Sectional drawing of the antistatic component in Embodiment 1 of this invention External perspective view of the anti-static component Equivalent circuit diagram of the static electricity countermeasure parts Schematic exploded perspective view of the static electricity countermeasure component Circuit diagram of electrostatic test in embodiment 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Varistor part 11a, 11b Internal electrode 12a, 12b External electrode 13a, 13b Via conductor 14, 14a, 14b, 14c Varistor layer 15 Ceramic insulation board 16 Protection layer 101 Power supply 102, 106 Resistance 103, 105 Switch 104 Capacity box 107 Ground line 108 Signal Line 109 Evaluation Sample 110 Protected Device 201 Varistor 202 Input / Output External Electrode 203 Ground External Electrode

Claims (6)

A ceramic insulating substrate, a varistor layer formed by sintering and integrating on the ceramic insulating substrate, an internal electrode, and a via conductor, and at least a pair of external electrodes provided on the outer surface of the varistor portion. The internal electrode has at least a pair of internal electrodes provided so as to face each other with the varistor layer interposed therebetween, and the external electrode and the internal electrode are electrically connected by the via conductor, and the varistor portion Anti-static parts with a thickness of 100 microns or less. The antistatic component according to claim 1, wherein a protrusion of the connection portion between the via conductor and the external electrode on the outer surface of the varistor portion is 3 μm or less. The antistatic component according to claim 1, wherein a protrusion of the connection portion between the via conductor and the external electrode in the varistor layer is 10 μm or less. The antistatic component according to claim 1, wherein the via conductor has a diameter of 120 microns or less. The antistatic component according to claim 1, wherein the via conductor is formed using a silver paste having a silver content of 85% or less. The antistatic component according to claim 1, further comprising a protective layer on the outer surface of the varistor portion.

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